Yep...

echo "1-2 2009-08-29 08:54:42;2-3 2009-09-02 01:29:29;3-4 2009-09-03 0
+8:24:46;4-5 2009-09-10 08:50:28;5-6 2010-06-29 08:26:43;6-7 2010-09-0
+3 10:45:47;7-8 2012-04-01 23:00:22;8-9 2012-04-28 12:09:22;9-10 2012-
+05-30 03:34:59;10-11 2014-11-30 09:34:57;11-12 2015-06-17 08:24:20" |
+ \
\
perl -nE '@a=split(/;/);for(@a){($a,$b)=split(/\s+(?=\d{4})/);say "$a:
+ $b";}'

1-2: 2009-08-29 08:54:42
2-3: 2009-09-02 01:29:29
3-4: 2009-09-03 08:24:46
4-5: 2009-09-10 08:50:28
5-6: 2010-06-29 08:26:43
6-7: 2010-09-03 10:45:47
7-8: 2012-04-01 23:00:22
8-9: 2012-04-28 12:09:22
9-10: 2012-05-30 03:34:59
10-11: 2014-11-30 09:34:57
11-12: 2015-06-17 08:24:20
#      ^^^^^^^^^^ <- today of all days :)
[download]

:)

And here it is in SQL, should you want to use some FUNctions on the data.

Should work in most RDBMS's, as long as they support recursive CTEs. Just replace the initial string with your own. And remove or replace "FROM Dual" with whatever works in your RDBMS.

WITH
    Levels(String)
AS
    (
     SELECT
        '1-2 2011-11-15 07:42:33;2-3 2011-11-27 13:51:37;3-4 2011-12-0
+6 07:12:37;4-5 2011-12-09 15:28:52;5-6 2011-12-30 10:53:44;6-7 2012-0
+2-02 07:06:41;7-8 2012-03-20 06:36:12;8-9 2012-05-25 11:46:56;9-10 20
+12-08-14 06:04:53;10-11 2013-09-04 07:38:12;11-12 2014-03-26 06:30:49
+;12-13 2014-06-18 10:51:18;13-14 2014-11-13 14:14:53;14-15 2015-06-10
+ 09:12:30'
     FROM
        Dual
    ),
    Split(Lvl, When, String)
AS
    (
     SELECT
        SUBSTR(String, INSTR(String, '-') + 1, 2),
        REPLACE(SUBSTR(String, INSTR(String, '-') + 03, 20), ';'),
        REPLACE(SUBSTR(String, INSTR(String, '-') + 23), ';', ' ')
     FROM
        Levels
     UNION ALL
     SELECT
        CAST(Split.Lvl + 1 AS VARCHAR2(2)),
        SUBSTR(Split.String, INSTR(Split.String, '-') + 03, 20),
        SUBSTR(Split.String, INSTR(Split.String, '-') + 23)
     FROM
        Split,
        Levels
     WHERE
        Split.String IS NOT NULL
    )
SELECT
    Lvl,
    When
FROM
    Split;
[download]