Kinda OT: Market Capitalization is the total amount that all the shares of stock for a company is worth. Is there a term or measure for how much people have actually paid for the stock?

ie, as a founder I have 20% of the stock, but I never paid for it. As the stock goes up, the highest bids raise the nominal value for the whole body, but for most of that value (for a startup at least), the stock owner has not had to pay anything.