I don't open balanced 12 counts. However I played with a partner who used any excuse to open for about a year. After every game, I reviewed the hand records and noted our result, and the top for the board, for every board where we had the option of bidding or passing a balanced 12 count. I entered them into a spreadsheet. On the hands that I passed we averaged 55%. On the hands where partner opened we averaged 38%. Does anybody else have any statistics?