Solve the following sql problem:
Find the average number of downloads for Single-Tables released by '2Pac' between 2001 and 2013.

Schema:
SCHEMA:
- Table: torrents
  - Column: groupName
    - Samples: [superappin&#39;, spiderap / a corona jam, rapper&#39;s delight, rap-o clap-o / el rap-o clap-o, christmas rappin&#39;]
  - Column: totalSnatched
    - Samples: [239, 156, 480, 200, 109]
  - Column: artist
    - Samples: [grandmaster flash & the furious five, ron hunt & ronnie g & the sm crew, sugarhill gang, joe bataan, kurtis blow]
  - Column: groupYear
    - Samples: [1979, 1979, 1979, 1979, 1979]
  - Column: releaseType
    - Samples: [single, single, single, single, single]
  - Column: groupId
    - Samples: [720949, 728752, 18513, 756236, 71818958]
  - Column: id
    - Samples: [0, 1, 2, 3, 4]
- Table: tags
  - Column: index
    - Samples: [0, 1, 2, 3, 4]
  - Column: id
    - Samples: [0, 0, 0, 2, 2]
  - Column: tag
    - Samples: [1970s, funk, disco, 1970s, new.york]

SELECT AVG(totalSnatched) FROM torrents WHERE artist LIKE '2Pac' AND releaseType LIKE 'Single' AND groupYear BETWEEN 2001 AND 2013