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          512        193 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4347       1500 
1996         3593       1262 
1997         2334        796 
1998        23309       9826 
1999        14583       5594 
2000        40639      16872 
2001        41643      16241 
2002        32766      14643 
2003        61707      25575 
2004        48479      18599 
2005        86531      26586 
2006       112026      35768 
2007       206602      63278 
2008       127529      36256 
2009       103813      29152 
2010       120472      33429 
2011       181335      50137 
2012       168407      46590 
2013       261833      74258 
2014       648657     165422 
2015       754221     200132 
2016       577763     154191 
2017       610927     163229 
2018       407749     114261 
2019       932208     227284 
2020       702012     180294 
2021       911003     218650 
2022       680082     194519 
2023       617905     177845 
2024       138089      39569