Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          492        186 
1992          770        310 
1993         1356        504 
1994         1916        698 
1995         3324       1156 
1996         3559       1250 
1997         2315        790 
1998        23170       9773 
1999        14481       5552 
2000        40121      16638 
2001        42424      16451 
2002        32097      14358 
2003        60277      25021 
2004        47528      18231 
2005        83713      25750 
2006       108248      34656 
2007       199138      61260 
2008       120526      34361 
2009        98710      27773 
2010       114074      31750 
2011       169209      46848 
2012       158912      43978 
2013       238325      67744 
2014       581089     149243 
2015       703202     186494 
2016       677147     175830 
2017       575910     155733 
2018       376453     105591 
2019       902546     220800 
2020       652046     166429 
2021       870947     207672 
2022       645518     184818 
2023       593074     169690 
2024       371574     107968