I see that you offer no source for your assertion that mental health admissions due to cannabis use have increased, and it is the DUE part of this statement that i think you should explain, as i think the link is highly arguable. Yes a lot of people with mental health issues have used or do use cannabis BUT did this cause the problem - or could it just be that many many people do use this drug in the first place AND that those with mental health problems use the drug to control their feelings to some extent.
Cannabis is one of the most commonly used drugs BUT nicotine is much much more commonly used, here again you will find that patients with mental illness use this a lot more than health people, and where schizophrenia is concerned the rate of smoking is extraordinarily high with extimates ranging from 50 - 85% (Dalack, Healy, and Meador-Woodruff, 1998). However instead of simply stating that smoking cigarettes causes schizophrenia it is much more useful to question "WHY" do schizophrenics smoke - studies in this area suggest that these patients are in someways able to alleviate their symptoms through this drug use (relaxation, focus).
I think it can be misleading to to band round statistics without first examining the possibility that though linked one is not the cause of the other - for example there is a strong relationship between the number of ice creams sold and the number of people who drown each month, but this doesn't mean the to are related, the fact is probably that warm weather increases ice cream sales and also increases the number of people swimming to cool down which in turn leads to more drownings.
I think the arguments surrounding cannabis use and mental health are complex but are not really helped by biast
question construction.