Retail Commercial Truck Dealership. During the six months ended June 30, 2021, North American sales of Class 6-8 medium- and heavy-duty trucks, the principal vehicles for our PTG business, increased 29.7% from the same period last year to 204,557 units. The Class 6-7 medium-duty truck market increased 16.1% to 66,200 units, and Class 8 heavy-duty trucks, the largest North American market, increased 37.4% to 138,357 units from the same period last year. The Class 8 heavy-duty market in North America is expected to increase from 233,000 units in 2020 to approximately 294,000 units in 2021 representing an increase of 28% driven by strong freight demand, an improving economy, and replacement demand.
Commercial Vehicle Distribution. During the six months ended June 30, 2021, the Australian heavy-duty truck market reported sales of 5,790 units, representing an increase of 17.7% from the same period last year, while the New Zealand market reported sales of 1,448 units, representing an increase of 15.4% from the same period last year. We expect the commercial vehicle and power systems markets to remain resilient in 2021 and continuing benefits from sales of replacement or upgraded engines.
Penske Transportation Solutions. A majority of the PTS business is generated by multi-year contracts for full-service leasing, contract maintenance, and logistics services. We expect continued resilient performance throughout 2021 as PTS has experienced increased levels of utilizations and profitability as business conditions improved as compared to the same period last year.
As described in “Forward-Looking Statements,” there are a number of factors that could cause actual results to differ materially from our expectations. See Part II, “Item 1A. Risk Factors.”
Operating Overview
Automotive and commercial truck dealerships together represent over 95% and 75% of our revenue and our earnings before taxes, respectively. Income from our PTS investment represents over 20% of our earnings before taxes. New and used vehicle revenues typically include sales to retail customers, fleet customers, and leasing companies providing consumer leasing. We generate finance and insurance revenues from sales of third-party extended service contracts, sales of third-party insurance policies, commissions relating to the sale of finance and lease contracts to third parties, and the sales of certain other products. Service and parts revenues include fees paid by customers for repair, maintenance and collision services, and the sale of replacement parts and other aftermarket accessories as well as warranty repairs that are reimbursed directly by various OEMs.
Our gross profit tends to vary with the mix of revenues we derive from the sale of new vehicles, used vehicles, finance and insurance products, and service and parts transactions. Our gross profit varies across product lines with vehicle sales usually resulting in lower gross profit margins and our other revenues resulting in higher gross profit margins. Factors such as inventory and vehicle availability, customer demand, consumer confidence, unemployment, 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 increased $3,336.4 million and $629.8 million, or 91.4% and 113.9%, respectively, during the three months ended June 30, 2021, and $4,101.1 million and $766.3 million, or 47.4% and 57.6%, respectively, during the six months ended June 30, 2021, compared to the same periods in 2020. See “COVID-19 Disclosure” above.
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 increased revenue and gross profit by $313.2 million and $47.3 million, respectively, for the three months ended June 30, 2021, and increased revenue and gross profit by $514.9 million and $76.8 million, respectively, for the six months ended June 30, 2021. Foreign currency average rate fluctuations increased earnings per share from continuing operations by approximately $0.11 per share for the three