(Datepicker) คำถามจะลดค่า Previousyear ของ $DateStart AND $DateEnd ลงได้อย่างไร โดยส่งมาจากฟอร์มเดียวกัน

public function show(Request $request) {

		$DateStart = $request->DateStart;
		$DateEnd = $request->DateEnd;

		$nowyear = date('Y');
		$startyear = 2017;
        
$bargraph = DB::select("
SELECT * FROM
    (SELECT count(tbmaster.id) as Previousyear
        FROM TB_INFO tbinfo
        LEFT JOIN TB_MASTER tbmaster
        ON tbinfo.id = tbmaster.id
        LEFT JOIN TB_NAME  tbname
        ON tbinfo.id = tbname.id
        WHERE tbinfo.datetime  is not null
        AND tbinfo.datetime  BETWEEN '$DateStart' AND '$DateEnd'  // ลดค่าลง 1 ปี BETWEEN 2017-01-01 AND 2017-01-31
        AND tbmaster.CancleCode is not null
        AND tbmaster.CancleCode in ('10','20')
        AND tbname.suff ='1'
    ) as Y1,
    (SELECT Count(tbmaster.id) as Currentyear
        FROM TB_INFO tbinfo
        LEFT JOIN TB_MASTER tbmaster
        ON tbinfo.id = tbmaster.id
        LEFT JOIN TB_NAME  tbname
        ON tbinfo.id = tbname.id
        WHERE tbinfo.datetime  is not null
        AND tbinfo.datetime  BETWEEN '$DateStart' AND '$DateEnd' //รับค่าจากฟอร์มปีปัจจุบัน BETWEEN 2018-01-01 AND 2018-01-31
        AND tbmaster.CancleCode is not null
        AND tbmaster.CancleCode in ('10','20')
        AND tbname.suff ='1'
     ) as Y2 ");

//dd($bargraph);

return view('myview')->with(['bargraph' => $bargraph, 'nowyear' => $nowyear, 'startyear' => $startyear]);
}

series: [
      @if (isset($bargraph))
      @for ($year = $nowyear; $year >= $startyear; $year--)
        { name: {{ $year }},
          data: [
        @for ($month = 1; $month <= 12; $month++)
          @foreach ($bargraph as $graph)
            @if ($year == $nowyear)
              {{ $graph->Currentyear }}
            @elseif($year >= $startyear)
              {{ $graph->Previousyear }},
            @endif
          @endforeach
        @endfor
            ]
        },
      @endfor
      @endif
        ]

series: [
    {
            name: 2018,
            data: [
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
            ]
    },
        {
            name: 2017,
            data: [
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
                24,
            ]
    },
        ]