Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Rank | 1-year peak | 5-year peak | 10-year peak | 15-year peak | 20-year peak |
| --- | --- | --- | --- | --- | --- |
| 1.0 | Bobby Fischer , 2881 | Garry Kasparov, 2875 | Garry Kasparov, 2863 | Garry Kasparov, 2862 | Garry Kasparov, 2856 |
| 2.0 | Garry Kasparov , 2879 | Emanuel Lasker, 2854 | Emanuel Lasker, 2847 | Anatoly Karpov, 2820 | Anatoly Karpov, 2818 |
| 3.0 | Mikhail Botvinnik , 2871 | José Capablanca, 2843 | Anatoly Karpov, 2821 | Emanuel Lasker, 2816 | Emanuel Lasker, 2809 |
| 4.0 | José Capablanca , 2866 | Mikhail Botvinnik, 2843 | José Capablanca, 2813 | José Capablanca, 2798 | Alexander Alekhine, 2781 |
| 5.0 | Emanuel Lasker , 2863 | Bobby Fischer, 2841 | Bobby Fischer, 2810 | Alexander Alekhine, 2794 | Viktor Korchnoi , 2766 |
Question:
What is the highest rank when Anatoly Karpov, 2820 is the 15-year peak?
Answer:
2.0