How many log switches

SELECT * FROM (
SELECT * FROM (
SELECT TO_CHAR(FIRST_TIME, 'DD/MM') AS "DAY"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '00', 1, 0), '99')) "00:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '01', 1, 0), '99')) "01:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '02', 1, 0), '99')) "02:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '03', 1, 0), '99')) "03:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '04', 1, 0), '99')) "04:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '05', 1, 0), '99')) "05:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '06', 1, 0), '99')) "06:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '07', 1, 0), '99')) "07:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '08', 1, 0), '99')) "08:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '09', 1, 0), '99')) "09:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '10', 1, 0), '99')) "10:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '11', 1, 0), '99')) "11:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '12', 1, 0), '99')) "12:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '13', 1, 0), '99')) "13:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '14', 1, 0), '99')) "14:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '15', 1, 0), '99')) "15:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '16', 1, 0), '99')) "16:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '17', 1, 0), '99')) "17:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '18', 1, 0), '99')) "18:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '19', 1, 0), '99')) "19:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '20', 1, 0), '99')) "20:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '21', 1, 0), '99')) "21:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '22', 1, 0), '99')) "22:00"
, SUM(TO_NUMBER(DECODE(TO_CHAR(FIRST_TIME, 'HH24'), '23', 1, 0), '99')) "23:00"
    FROM V$LOG_HISTORY
       WHERE extract(year FROM FIRST_TIME) = extract(year FROM sysdate)
          GROUP BY TO_CHAR(FIRST_TIME, 'DD/MM')
  ) ORDER BY TO_DATE(extract(year FROM sysdate) || DAY, 'YYYY DD/MM') DESC
  ) WHERE ROWNUM <31;

col STAT_NAME for a20
col VALUE_DIFF for 9999,999,999
col STAT_PER_MIN for 9999,999,999
set lines 200 pages 1500 long 99999999
col BEGIN_INTERVAL_TIME for a30
col END_INTERVAL_TIME for a30
set pagesize 40
set pause on
 
 
select hsys.SNAP_ID,
       hsnap.BEGIN_INTERVAL_TIME,
       hsnap.END_INTERVAL_TIME,
           hsys.STAT_NAME,
           hsys.VALUE,
           hsys.VALUE - LAG(hsys.VALUE,1,0) OVER (ORDER BY hsys.SNAP_ID) AS "VALUE_DIFF",
           round((hsys.VALUE - LAG(hsys.VALUE,1,0) OVER (ORDER BY hsys.SNAP_ID)) /
           round(abs(extract(hour from (hsnap.END_INTERVAL_TIME - hsnap.BEGIN_INTERVAL_TIME))*60 +
           extract(minute from (hsnap.END_INTERVAL_TIME - hsnap.BEGIN_INTERVAL_TIME)) +
           extract(second from (hsnap.END_INTERVAL_TIME - hsnap.BEGIN_INTERVAL_TIME))/60),1)) "STAT_PER_MIN"
from dba_hist_sysstat hsys, dba_hist_snapshot hsnap
 where hsys.snap_id = hsnap.snap_id
 and hsnap.instance_number in (select instance_number from v$instance)
 and hsnap.instance_number = hsys.instance_number
 and hsys.STAT_NAME='user commits'
 order by 1;