activities on our existing credit facilities were primarily to fund our investment in the container lease fleet, make business acquisitions, pay dividends and manage our operating assets and liabilities. In addition, in FY 2018, $81.5 million was borrowed from the Deutsche Bank Credit Facility to repay the ANZ/CBA Credit Facility (see Note 5 of Notes to Condensed Consolidated Financial Statements). Deferred financing costs related to the Bison Capital Notes and Deutsche Bank Credit Facility totaled $3.8 million in FY 2018 versus $0.4 million in FY 2019, which primarily related to the Senior Notes consent solicitation and an amendment to Wells Fargo Credit Facility. Cash of $1.8 million was used during both periods to pay dividends on primarily our Series C Preferred Stock; and, in FY 2018, Royal Wolf paid a capital stock dividend of $1.0 million to noncontrolling interests (see Note 3 of Notes to Condensed Consolidated Financial Statements). In FY 2019, we received proceeds of $0.9 million from issuances of common stock on the exercises of stock options versus only $34,000 in FY 2018.
Asset Management
Receivables and inventories were $55.0 million and $37.0 million at December 31, 2018 and $50.5 million and $22.7 million at June 30, 2018, respectively. At December 31, 2018, DSO in trade receivables were 39 days and 45 days in the Asia-Pacific area and our North American leasing operations, as compared to 35 days and 47 days at June 30, 2018, respectively. The $14.3 million increase in inventories was primarily due to the timing of receipts of sale and fleet units to fulfill known increased portable storage demand. Effective asset management is always a significant focus as we strive to apply appropriate credit and collection controls and maintain proper inventory levels to enhance cash flow and profitability.
The net book value of our total lease fleet was $448.5 million at December 31, 2018, as compared to $429.4 million at June 30, 2018. At December 31, 2018, we had 96,600 units (24,564 units in retail operations in Australia, 8,841 units in national account group operations in Australia, 12,789 units in New Zealand, which are considered retail; and 50,406 units in North America) in our lease fleet, as compared to 85,812 units (24,037 units in retail operations in Australia, 8,046 units in national account group operations in Australia, 10,222 units in New Zealand, which are considered retail; and 43,507 units in North America) at June 30, 2018. At those dates, 81,046 units (20,949 units in retail operations in Australia, 7,746 units in national account group operations in Australia, 10,891 units in New Zealand, which are considered retail; and 41,460 units in North America); and 68,712 units (20,102 units in retail operations in Australia, 5,038 units in national account group operations in Australia, 8,705 units in New Zealand, which are considered retail; and 34,867 units in North America) were on lease, respectively.
In the Asia-Pacific area, the lease fleet was comprised of 38,535 storage and freight containers and 7,659 portable building containers at December 31, 2018; and 34,507 storage and freight containers and 7,798 portable building containers at June 30, 2018. At those dates, units on lease were comprised of 34,384 storage and freight containers and 5,202 portable building containers; and 28,301 storage and freight containers and 5,544 portable building containers, respectively.
In North America, the lease fleet was comprised of 35,694 storage containers,4,836 office containers (GLOs), 4,219 portable liquid storage tank containers, 4,484 mobile offices and 1,173 modular units at December 31, 2018; and 29,518 storage containers,4,216 office containers (GLOs), 4,147 portable liquid storage tank containers, 4,447 mobile offices and 1,179 modular units at June 30, 2018. At those dates, units on lease were comprised of 29,467 storage containers, 3,976 office containers, 3,260 portable liquid storage tank containers, 3,765 mobile offices and 992 modular units; and 23,040 storage containers, 3,620 office containers, 3,405 portable liquid storage tank containers, 3,792 mobile offices and 1,010 modular units, respectively.
Contractual Obligations and Commitments
Our material contractual obligations and commitments consist of outstanding borrowings under our credit facilities discussed above and operating leases for facilities and office equipment. We believe that our contractual obligations have not changed significantly from those included in the Annual Report.
Off-Balance Sheet Arrangements
We do not maintain any off-balance sheet transactions, arrangements, obligations or other relationships with unconsolidated entities or others that are reasonably likely to have a material current or future effect on our financial condition, changes in financial condition, revenues or expenses, results of operations, liquidity, capital expenditures or capital resources.
40