New zinc15 questions

These are questions that we can only answer in the last week, due to new tools.

1. what is the most popular pains pattern in zinc?

2. how many pains patterns have zero hits?

3. what is the most popular pains pattern in chembl20 ?

4a how many rings are there?

4. what are the 10 most popular rings in ZINC? ChEMBL? Drugs? Biogenic? Metabolites?

5. What rings are found in metabolites but not in ZINC (bioactives)

6. What rings are found in biogenic but not in ZINC (bioactives)

7. What are the tool compounds for each target?