I don't have the charts at my fingertips, but I'm sure someone does. Over the last 10 years, until very recently, gold was $200-400/oz, and I think silver was $2-5. The old, "fixed" price, from 1933-c.1975 was $35 for gold and $1.29 for silver, or about 30-1.
It is true that at the top of the speculative bubble in 1979-80, Gold was 850 and silver almost 50, or close to 16-1, but Silver ws much more "bubbled", and fell much faster, so the ratio grew back towards 30-1 or so.
I'm not saying that there is any "right" ratio (in fact, I would say that there isn't), but I think that the times when a free market price of silver was as much as 1/16 that of gold have been pretty rare -- but I'm sure someone has the charts with real answer.
Weekly Gold/Silver Ratio for the past 25 years.
"Fixing" the ratio of silver to gold when they were both used as money caused no end of problems to the government, since the founding of the republic. Set too high/low, ss the relative values fluctuated on the world market, it became profitable to buy and sell one for the other, causing one or the other to disappear from circulation. "Free Silver" was an attempt by easy-money adherents to force the government to buy and issue silver dollars, which theoretically benefited debtors, farmers and Western mining interests.