NEW YORK (Reuters) - The ranks of U.S. retail investors have sky-rocketed in the past year as online platforms have proliferated and fees have disappeared while the pandemic has left people stuck at home with extra savings and few places to put it to use profitably. But how big is the surge in retail trading? Analysts and executives say it is difficult to peg an exact figure, but here are some numbers to put it in perspective: * 25%+: The percentage of overall market trades made by retail investors in July and August 2020, according to Virtu Financial, one of the world’s largest retail market makers. In January 2020 retail was 17.1% of the market. Virtu’s data only goes to November, but retail investors appear to have played an even bigger role in 2021. Jefferies analyst Daniel Fannon said on Friday retail can represent up to 32% of total U.S. equity volume. (Graphic: Retail trading as percentage of overall trading Jan-Nov 2020: ) * 24.5 BILLION: The all-time volume record for U.S. cash equities, set on Wednesday amid the GameStop frenzy. Options volumes also hit a record high that day, with 57.1 million contracts traded. For both stocks and options, the records were roughly double the average daily volume (ADV) from 2020 and triple the ADV from 2019, according to Piper Sandler analyst Richard Repetto. * 8.2 MILLION: The average number of daily trades made by customers of Charles Schwab Corp the week of Jan. 11-15. In 2020, Schwab clients peaked at 7.8 million trades on Nov. 9, the company said. * 31 YEARS: The median age of user of Robinhood, one of the original commission-free online brokerages. More young adults are joining. Apex Clearing, which helps facilitate trades for brokerages, told Reuters around 1 million of new accounts it opened last year belonged to Gen Z investors, with an average age of 19. * ~$15.5 TRILLION: Total client assets at two of the top retail-focused brokerages. Fidelity Investments had $8.8 trillion in customer assets at the end of the third quarter, up from $8.3 trillion at the end of 2019. Schwab had $6.69 trillion in client assets as of Dec. 31, and 29.6 million brokerage accounts, up 66% and 140%, respectively, from a year earlier. MORE THAN 100 MILLION: The number of users/accounts combined at six of the top online brokerages, according to the most recent data. Fidelity: 32.5 million brokerage accounts Vanguard: More than 30 million users Schwab: 29.6 million accounts Webull: 15 million users Robinhood: 13 million users Interactive Brokers: 1.1 million accounts