The percentage of high school graduates who attend a 2-year college varies from year to year and depends on the country and data source. There's no single definitive answer. You'll find different numbers depending on how the data is collected and defined (e.g., immediately after high school, within a certain timeframe, including those who transfer to 4-year institutions).
To find a relevant statistic, you'd need to specify the country and look for data from sources like the National Center for Education Statistics (NCES) in the U.S. or equivalent organizations in other countries.