Jill incorporates her sole proprietorship by exchanging all the proprietorship's assets for the stock of JJ Corporation, a new corporation. Jack is the only other shareholder of the JJ Corporation, and he contributes his legal services in exchange for stock. To qualify for tax-free incorporation, Jill and Jack must be in control of JJ immediately after the exchange. What is the minimum percentage of JJ's stock that Jill may own to qualify as "control" for this purpose?