ZCL was about 5% of ZCash price at it's peak from memory - but it was in anticipation of ZEN that it rose. There's rising volume now, I think we haven't seen the lowest lows now, but I think we're not that far off, if volume continues to rise everyone who wanted to sell will have sold.
I tend to view Ethereum Classic's percentage of Eth's value as a guide. Not sure what it is now, last time I looked somewhere 15%.
Is it worth to stack Zen ? Because the price is going down day by day
-15,73 % nice

Personally, I moved my assets from ZCL and ZEN completely.
Just look at ZCL, for example, the thing was about 10% of ZEC's price once, and never recovered after this ZEN disaster happened. Now it is less than 1% worth of ZEC.
To me, that means people doesn't trust the devs of both projects anymore, even to the "independent", "community powered", "founders reward disabled" ZCL.
Wanna a "private bitcoin" - ZEC is like the gold, HUSH is like the new silver. Particularly HUSH, the thing isn't even listed by Bittrex yet, but it has basically the same price as ZCL already.