China's benchmark Shanghai Composite share average has rallied some 58% over the past 12 months.

And the market players driving that rally are a set of inexperienced retail investors who lack even a high school education, according to a survey.

More than two thirds of China's new equity investors exited the education system by middle school — which in China is around the age of 15, data from the China Household Finance Survey (CHFS) showed.

More than 30% exited at age 12 or below.

Household wealth for new investors is about half the level of existing investors, the CHFS also showed.

The world's most populous nation is sitting on a mountain of savings, and the Chinese are flooding the stock market as alternative investment options are limited.

While the CHFS data adds to the notion of a rally being fueled by inexperienced retail investors, that does not mean it cannot be sustained, Bloomberg reported.

However, the survey's data does suggest that the trajectory of China's equity markets will be unpredictable, and prone to sudden reversals as sentiment shifts.

The CHFS is headed by Professor Li Gan of the Southwestern University of Finance and Economics. The survey was conducted at the end of 2014 and covers some 4,000 households across the country.