Year ended December 31, 2020 compared to year ended December 31, 2019. General and administrative expenses increased by $3.5 million, or 19%, to $21.8 million for the year ended December 31, 2020. The change was primarily due to a $2.1 million increase in compensation expenses, a $0.6 million increase in operating expenses related to the home office building, and a $0.5 million increase in business acquisition transaction costs. General and administrative expenses decreased from 5% to 4% as a percentage of revenue year over year, as we experienced scale in our support functions.
To test the estimated fair value of the technology and customer-related intangible assets, we performed audit procedures that included, among others, evaluating the Company's selection of the valuation methodology, evaluating the methods and significant assumptions used by the Company's valuation specialist, and evaluating the completeness and accuracy of the underlying data supporting the significant assumptions and estimates. We involved our valuation specialists to assist with our evaluation of the methodology used by the Company and significant assumptions included in the fair value estimates. For example, we compared the key assumptions to third-party industry projections for similar market participants. Specifically, when assessing the key assumptions, we focused on revenue growth rates, attrition assumptions and basis for the discount rate used.
Receivables are comprised of trade receivables and other miscellaneous receivables. Accounts and other receivables are carried at their estimated collectible amounts. Accounts receivable balance is primarily related to the Company’s other business segment where the Company generates revenue from underwriting policies through unaffiliated general agents. These policies are typically annual policies, with monthly payment terms through the end of the twelve-month period. The Company had $94.2 million and $50.0 million accounts receivable associated with underwriting these policies as of December 31, 2020 and 2019, respectively.
In the following tables, the cumulative number of veterinary invoices represents the total number received as of December 31, 2020, by year the veterinary invoice relates to, referred to as the year of occurrence. If a pet is injured or becomes ill, multiple trips to the veterinarian may result in several invoices. Each of these veterinary invoices is included in the cumulative number, regardless of whether the veterinary invoice was paid. Information for years 2017 through 2019 is provided as required supplementary information. Amounts in these tables are presented on a constant currency basis to remove the impact of changes in the foreign currency exchange rate on development. The cumulative expenses as of the end of each year are revalued using the currency exchange rate as of December 31, 2020.
As of December 31, 2020, stock options outstanding and stock options exercisable had a weighted average remaining contractual life of 4.1 years and 4.0 years, respectively.
The fair value of options vested were as follows for the years ended December 31, 2020, 2019, and 2018. The Company didn't grant any stock options in these three years.