I've created the following SEDE query which calculates the reputation averages of users on a particular site. It also optionally excludes "new" users (users with rep of 1 or 101 so note 100% accurate).

DECLARE @exclude_new_users INT
SET @exclude_new_users = ##ExcludeNewUsers:int?0##

DECLARE @excluded_rep_table TABLE (Rep INT)
INSERT INTO @excluded_rep_table VALUES (1),(101)

DECLARE @rep_table TABLE (Reputation INT)
INSERT INTO @rep_table (Reputation)
    SELECT Reputation
    FROM USERS
    WHERE Reputation <>
        CASE WHEN @exclude_new_users = 0
        THEN -1
        ELSE (SELECT IIF (EXISTS (SELECT Rep FROM @excluded_rep_table WHERE Rep = Reputation), Reputation, -1))
        END

SELECT COUNT(*) AS [Total Users],
       MIN(Reputation) AS [Minimum],
       MAX(Reputation) AS [Maximum],
       SUM(Reputation) / COUNT(*) AS [Mean],
       (
           SELECT TOP 1 Reputation
           FROM @rep_table
           GROUP BY Reputation
           ORDER BY COUNT(Reputation) DESC
       ) AS [Mode],
       (
           SELECT
           (
               (
                   SELECT MAX(Reputation)
                   FROM
                   (
                       SELECT TOP 50 PERCENT Reputation
                       FROM @rep_table
                       ORDER BY Reputation
                   ) AS [Bottom Half]
               )
               +
               (
                   SELECT MIN(Reputation)
                   FROM
                   (
                       SELECT TOP 50 PERCENT Reputation
                       FROM @rep_table
                       ORDER BY Reputation DESC
                   ) AS [Top Half]
               )
           ) / 2
       ) AS [Median],
       STDEVP(Reputation) AS [Standard Deviation]
FROM @rep_table

I'm quite the SQL novice and mainly did this for some practice so I'm really after general feedback: ways to improve/optimise the code but also to improve the layout, it looks ugly and I can't imagine it fits with style guidelines.