Table:
team
from
to
record

g
w
d
l
win %
ref

fc wil
1 july 1988
30 june 1993
-

grasshoppers
1 july 1993
19 november 1997
161
88
41
32
54.66
none

tottenham hotspur
20 november 1997
6 september 1998
30
10
8
12
33.33
none

basel
1 july 1999
27 may 2009
498
289
115
94
58.03
none

vfb stuttgart
6 december 2009
13 october 2010
36
20
7
9
55.56
none

young boys
8 may 2011
30 april 2012
40
16
15
9
40.00
none

al-ahli
1 july 2014
1 july 2016
82
57
19
6
69.51
none

al-ahli
2 october 2016
20 june 2017
37
24
6
7
64.86
none

zamalek sc
13 july 2018
present
45
26
13
6
57.78
none

total
904
512
219
173
56.64
-

Statement: christian gross was manager of basel from 1 july 1999 to 27 may 2009.
Question: when did christian gross become the manager of basel?
Answer: 1 july 1999