The trading volume there has gone up 10 times since December 1993 - and the market capitalization is up 30 times. But this is because of the performance of the general economy in Slovenia. In Croatia, the government is privatizing its holdings in state owned companies by auctioning shares to the public through the Zagreb Stock Exchange. This has helped it a lot. Newly-established stock exchanges are highly volatile and very dangerous.
Volatility goes hand in hand with risk.
They are long term investments. Since 1988, they outperformed the more established stock exchanges in the world, like Wall Street. But these stock exchanges are growing fast, they are cheap by any measure and they are the best investment that a country can make in its own future.