Queries quality and percentage

#
# Table: Queries
# +-------------+---------+
# | Column Name | Type    |
# +-------------+---------+
# | query_name  | varchar |
# | result      | varchar |
# | position    | int     |
# | rating      | int     |
# +-------------+---------+
# This table may have duplicate rows.
# This table contains information collected from some queries on a database.
# The position column has a value from 1 to 500.
# The rating column has a value from 1 to 5. Query with rating less than 3 is a poor query.
# We define query quality as:
# The average of the ratio between query rating and its position.
# We also define poor query percentage as:
# The percentage of all queries with rating less than 3.
# Write a solution to find each query_name, the quality and poor_query_percentage.
# Both quality and poor_query_percentage should be rounded to 2 decimal places.
# Return the result table in any order.
# The result format is in the following example.
# Example 1:
# Input:
# Queries table:
# +------------+-------------------+----------+--------+
# | query_name | result            | position | rating |
# +------------+-------------------+----------+--------+
# | Dog        | Golden Retriever  | 1        | 5      |
# | Dog        | German Shepherd   | 2        | 5      |
# | Dog        | Mule              | 200      | 1      |
# | Cat        | Shirazi           | 5        | 2      |
# | Cat        | Siamese           | 3        | 3      |
# | Cat        | Sphynx            | 7        | 4      |
# +------------+-------------------+----------+--------+
# Output:
# +------------+---------+-----------------------+
# | query_name | quality | poor_query_percentage |
# +------------+---------+-----------------------+
# | Dog        | 2.50    | 33.33                 |
# | Cat        | 0.66    | 33.33                 |
# +------------+---------+-----------------------+
# Explanation:
# Dog queries quality is ((5 / 1) + (5 / 2) + (1 / 200)) / 3 = 2.50
# Dog queries poor_ query_percentage is (1 / 3) * 100 = 33.33
# Cat queries quality equals ((2 / 5) + (3 / 3) + (4 / 7)) / 3 = 0.66
# Cat queries poor_ query_percentage is (1 / 3) * 100 = 33.33
#

# Write your MySQL query statement below

SELECT query_name,
  ROUND(AVG(rating * 1.0 / position), 2) AS quality,
  ROUND(100.0 * SUM(rating < 3) / COUNT(*), 2) AS poor_query_percentage
FROM Queries
WHERE query_name IS NOT NULL
GROUP BY query_name;