open outcry system is only used in futures trading & there r probably more futures contracts traded, in variety & quantity, in US than all other mkts combined
most locals trade on short time frames from hours 2 minutes 2 even seconds, rarely holding positions long, therefore increasing the volume & narrowing the buy/sell spreads, making it easier for the public 2 enter/exit the market
they r the lubicants of the mkt. they could account for 1/3 or more of daily volume
more and more exchanges r switching 2 electronic trading which doesn't need open outcry but would often keep the local system intact
HK gold mkt used open outcry system before. so did malaysia and singapore futures exchanges till switching 2 electronic trading a few years ago. but US futures exchanges r still using the old & noisy but probably the most transparent & exciting way of trading: open outcry