EASY , SIMPLE SOLUTION
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n\nselect round (count(*)::numeric / (select count (distinct player_id) from activity) , 2) fraction\nfrom activity\nwhere (player_id , event_date) in (\n        select player_id , min(event_date) + 1 firstLog \n        from activity \n        group by 1 )\n\n\n```
['PostgreSQL']