general economic conditions, seasonality, weather, credit availability, fuel prices, and manufacturers’ advertising and incentives also impact the mix of our revenues, and therefore influence our gross profit margin.
The results of our commercial vehicle distribution business in Australia and New Zealand are principally driven by the number and types of products and vehicles ordered by our customers.
Aggregate revenue and gross profit decreased $184.5 million and $22.0 million, or 3.1% and 2.5%, respectively, during the three months ended June 30, 2019 and decreased $367.0 million and $34.9 million, or 3.1% and 2.0%, respectively, during the six months ended June 30, 2019, compared to the same periods in 2018. The decreases are largely attributable to same-store decreases in new and used vehicle revenue and gross profit, partially offset by increases in service and parts and Retail Commercial Truck revenue and gross profit.
As exchange rates fluctuate, our revenue and results of operations as reported in U.S. Dollars fluctuate. For example, if the British Pound were to weaken against the U.S. Dollar, our U.K. results of operations would translate into less U.S. Dollar reported results. Foreign currency average rate fluctuations decreased revenue and gross profit by $147.9 million and $20.9 million, respectively, for the three months ended June 30, 2019, and decreased revenue and gross profit by $328.5 million and $46.8 million, respectively, for the six months ended June 30, 2019. Foreign currency average rate fluctuations decreased earnings per share from continuing operations by approximately $0.03 per share for the three months ended June 30, 2019 and decreased earnings per share from continuing operations by approximately $0.07 per share for the six months ended June 30, 2019. Excluding the impact of foreign currency average rate fluctuations, revenue and gross profit decreased 0.6% and 0.1%, respectively, for the three months ended June 30, 2019, and decreased 0.3% and increased 0.7%, respectively, for the six months ended June 30, 2019.
Our selling expenses consist of advertising and compensation for sales personnel, including commissions and related bonuses. General and administrative expenses include compensation for administration, finance, legal and general management personnel, rent, insurance, utilities and other expenses. As the majority of our selling expenses are variable, and we believe a significant portion of our general and administrative expenses are subject to our control, we believe our expenses can be adjusted over time to reflect economic trends.
Floor plan interest expense relates to financing incurred in connection with the acquisition of new and used vehicle inventories that is secured by those vehicles. Other interest expense consists of interest charges on all of our interest-bearing debt, other than interest relating to floor plan financing, and includes interest relating to our retail commercial truck dealership and commercial vehicle distribution operations. The cost of our variable rate indebtedness is based on the prime rate, defined London Interbank Offered Rate (“LIBOR”), the Bank of England Base Rate, the Finance House Base Rate, the Euro Interbank Offered Rate, the Canadian Prime Rate, the Australian Bank Bill Swap Rate, or the New Zealand Bank Bill Benchmark Rate.
Equity in earnings of affiliates represents our share of the earnings from our investments in joint ventures and other non-consolidated investments, including PTL.
The future success of our business is dependent upon, among other things, general economic and industry conditions; our ability to consummate and integrate acquisitions; the level of vehicle sales in the markets where we operate; our ability to increase sales of higher margin products, especially service and parts sales; our ability to realize returns on our significant capital investment in new and upgraded dealership facilities; the success of our distribution of commercial vehicles, engines, and power systems; and the return realized from our investments in various joint ventures and other non-consolidated investments. See “Forward-Looking Statements” below.
Critical Accounting Policies and Estimates
The preparation of financial statements in accordance with accounting principles generally accepted in the United States of America requires the application of accounting policies that often involve making estimates and employing judgments. Such judgments influence the assets, liabilities, revenues and expenses recognized in our financial statements. Management, on an ongoing basis, reviews these estimates and assumptions. Management may determine