id: 3 yr ( 10, (0, 0, 6, 4)) (( 3.7, 3.4 ), ( 2.3, 4.0 ))
 +1                             +0 
                              |
                         2012  2015 |
                              |
+----+----+----+----+----2014--2018 16-+
                              |
                       2013      |
                              |
                              |
+    +    +    +    + 2017 +    +
                              |
                              |
                              |
                              |
+    +    +    +    +    +    +
                              |
              2011               |
                              |
                              |
+    +    +    +    +    +    +
           2019                  |
                              |
                              |
                              |
+    +    +    +    +    +    +
                              |
                              |
                              |
                              |
+    +    +    +    +    +    +
  2020                           |
                              |
 -11                             -12